smithers, have you driven and one or ridden in one?
That would be the first thing to do.
You may find that the car you test or get will already have some of the basics done like exhaust and boost restrictor removed and that might meet your immediate needs.
Power figures (and torque for that matter) are just numbers. People have different preferences around the feel of the car, response and top end power. Read the -5 or -7's thread for some great insight. From what I drove prior to getting mine, I found the GTR a little slow at the bottom end but thats just the different delivery from what I was used to. I came from a GT-T with high flow, front mount and power fc tuned for response. The car I tested was bog stock but dated (mileage wise). I ended up importing something with lower kms and some tasteful mods.
If you have any other questions, let me know